Self Sterility and Cross Sterility in the Apple. 75 



for cross pollination in the commercial production of apples. 

 If the relative set of the fruit is considered it is even more clear- 

 ly demonstrated that cross pollination is necessary in commer- 

 cial orcharding for of the 42 self fertilized which did set fruit 

 as shown in table 2, less than 16 set fruit in anything but neg- 

 ligible amounts. 



It is of some interest to examine the crosses which did not 

 set fruit a little further to determine if possible the reason why 

 they did not. Out of the 57 which did not prove compatible 

 about half (26) had enough trial crosses made to make it seem 

 likely that these crosses were nearly if not entirely, incompat- 

 ible. These crosses were Delicious x Grimes, Duchess x Bald- 

 win, Early Ripe x Chenango, Early Ripe x Kinnard, Ingram x 

 Rome, Ingram x Stayman, Lily of Kent x Paragon, Nickajack 

 x Stayman, Paragon x Bloomfield, Paragon x Lily of Kent, 

 Paragon x Stayman, Paragon x Winesap, Red June x Early 

 Ripe, Rome x Akin, Rome x Stayman, Stark x Red Astrachan, 

 Stayman x Doucin, Stayman x Gravenstein, Stayman x Lily of 

 Kent, Stayman x Missouri Pippin, Stayman x Paragon, Stay- 

 man x Winesap, Winesap x Lily of Kent, Winesap x Paragon, 

 Yellow Transparent x Stark, and Yellow Transparent x Stay- 

 man. It will be noted that the varieties Stayman, Winesap and 

 Paragon form the largest part of these sterile crosses. Stay- 

 man is known to be a seedling from the Winesap.* The Para- 

 gon is thought to have originated from the Winesapf crossed 

 by Limbertwig. If these facts represent the true state of af- 

 fairs it is entirely likely that the seedlings would also have the 

 incompatibility of the parents from which they sprang pro- 

 vided, of course, that sterility in the apple is inherited in a sim- 

 ilar manner to other known inheritance. 



It is of interest to note also that the variety Lily of Kent 

 enters into a number of these crosses. Lily of Kent x Paragon 

 and Paragon x Lily of Kent are reciprocally sterile. Lily of 

 Kent pollen is also sterile with Stayman and Winesap. So, 

 likewise, is the cross between Yellow Transparent x Stayman 

 and Stayman x Yellow Transparent reciprocally sterile. On 

 the other hand the crosses of Nickajack x Stayman and Red 

 June x Early Ripe are sterile but the reciprocal crosses are 



♦Beach, S. A., et al., 1905 The Apple of New York. vol. I, p. 318. 

 fBeach, S. A., et al., 1905 The Apple of New York. vol. I, p. 247. 



